The BOLT II hypersonic flight test may bring superfast global travel one step further
They may also provide more options to launch payloads in space than conventional rockets. Their speed and maneuverability mean they are able to serve a variety of military-related tactical possibilities as well.
Russia and China both claim to have launched hypersonic missiles; however, passenger aircraft that are hypersonic remains an unrealized dream, not a reality.
Read more: Hypersonic missiles are fuelling fears of a new superpower arms race.
Nevertheless, several types of hypersonic vehicles already exist, including rockets, planetary entry vehicles such as SpaceX’s Dragon capsule, and intercontinental ballistic missiles.
Is hypersonic travel a thing?
Hypersonic flight is more efficient than supersonic flight. The latter, in essence, is more speed than sound.
To break through the sound barrier – and even surpass “Mach 1” – you have to be able to travel faster than approximately 1,235km per hour or a kilometer in less than three seconds. Mach 2 speeds are twice as quick, and so on.
There is no clear Mach number that defines the line between hypersonic and supersonic flights. However, the Mach number 5 is typically regarded by aerospace engineers as the point where hypersonic speeds begin.
Hypersonic travel can cause additional issues that don’t occur at a higher speed for pedestrians. The most significant of these is the fact that the flow of air through the vehicle creates such a high amount of friction that the exterior of the craft may exceed 1,000 degrees Celsius.
Like all aircraft flying, flying is dependent on not having too much weight on the board. Therefore, specialist substances, either high-temperature ceramics or “ablative” materials that slowly disappear during flight, are required on the exterior of vehicles in order to protect the car from this heat, but still light enough for flying.
Hypersonic engines, also known as scramjets (supersonic combustion ramjets) must burn fuel in a supersonic flow. This is quite complex.
Artist’s image from the Boeing X-51A Waverider, a hypersonic test vehicle powered by a scramjet. U.S. Air Force
Another problem that has been recurring is hypersonic flight’s difficulty to accurately model due to the interplay among physical effects that are present when flying at extremely high speeds.
If you’re trying to comprehend everything, it is necessary to conduct actual flight tests, like the one we’re doing today. However, they are costly and technically challenging.
Read more: The race to hypersonic speed: will air passengers feel the benefits?
One of the more difficult hypersonic challenges is to determine what’s known as “the “boundary layer transition location.”
When an aircraft is flying through the air, a thin layer of air is formed around the surface, and it is pulled by the vehicle.
The “boundary layer” is very crucial since the majority of the heat is generated in this area, as well as an important portion of drag forces that try to slow down the car.
As the boundary layer expands across the length of the vehicle, the boundary layer will ultimately “transition” from the calm “laminar” flow near the front edge of the car and then to an explosive “turbulent” flow further downstream.